Portable belt abrading machine



July 14, 1942. A. c. BURLEIGH PORTABLE BELT ABRADING MACHINE 'Filed Dec.e, 1940 bym Patented July 14, 1942 UNITED STATES ATENT OFFICE PGR-TABLEBELT' ABRADENG .MACHINE Arthur C. Burleigh, Wellesley, Mass.

Application December 6, 19,40-, Serial No. 368,745

(Cl. 5-1-l7t) 6 Claims.

This invention relates to a portable belt abrading machine andparticularly to an abrading machine of this type in which the motor foroperating the belt is located within the supporting frame and betweenthe upper and lower runs of the belt. This construction has theadvantage that it results in a very compact machine with a relativelylow center of gravity.

rI'he `features wherein my improvements reside will be more fullyhereinafter set forth, and then pointed out in the appended claims.

In the drawing:

Fig. 1 is a sectional view through a sanding machine embodying myinvention, taken on substantially the line .I-I, Fig. 2.

Fig. 2 is a section on the line 2 2, Fig. 1.

Fig. 3 is a section on the line 3-3, Fig. 1, the tension pulley beingshown in elevation.

Fig. 4 Yis a section on lthe line II--4, Fig. l.

Fig. 5 is a section on the line 5-5, Fig. 1.

In the drawing, the abrading belt, which is indicated at I, passesarounda driving Lpulley 2 and an idler pulley 3, both of which are mounted ona suitable frame 4, the driving pulley 2 being at the rear end of theframe and the idler pulley 3 being at the front end thereof. This frameis formed with two side members 5 and 6 which are connected by a top orhood member 1 that covers the belt and pulley, and also `by a bottommember 8 which is shorter than the frame and underneath which the lowerrun or operative portion I2 of the abrading belt passes, said bottommem* ber 8 thus forming a presser member for holding said operativeportion 4of the abrading belt against the work. The side member 6 isrelatively short and is situated mid-way of the frame between thedriving `pulley 2 and the idler pulley 3.

The motor for operating the driving pulley 2 is indicated at 9. ing I0which is situated within the frame between the bottom member 8 and thehood or ytcp member 'I, and between the upper run II and lower run |32of the abrading belt I. This motor housing is shownas extending betweenthe side members 5 and -6 and as connected thereto.

The motor shaft is indicated at I3. It extends transversely of thefra-me, and one -end of it is journaled inthe bearing I4 carried by themotor housing, and the .other end is journaled in the -I bear-ing I5carried by the side member 5 of the frame and extends through said sidemember.

The driving connections between the motor shaft `*I3 and the drivingpulley 2 comprise a This is mounted in a motor housan intermediate gearIl mounted on a stud I8 carried by the frame side mem-ber 5, saidintermediate gear in turn meshing with a driving gear I 9 fast on theshaft 23 on which the pulley 2 is mounted. This shaft 20 is journaled insuitable bearings 2l, 22 carried by the side portion 5 of the frame, theend 23 of the shaft extending beyond the bearing 22 and having mountedthereon the hub 24 of the pulley 2, which hub is located centrally ofthe pulley. A

The idler pulley 3 is supported on an arm 55 which is secured to `andextends `forwardly from the motor housing Ill. For this purpose, saididler pulley is made in two sections 3a and 3b, each` of which issecured to the end of a shaft 52 which is journaled in the hub portion53 with which the arm 55 is provided at its outer end. The inner ends ofthe pulley sections 3a, 3b overlie the ends of the hubs and hence thepulley sections are only separated from each other by a distance equalto the transverse dimension of the arm 55. I will preferably provideballbearings 54 in the hub 53 for the shaft 52.

The frame or housing is provided with a handle 28 by which it may bemanipulated, and this handle may conveniently have a switch element 29for opening and closing the motor circuit.

The bottom portion 8 of the frame extends below the lower edge 35 of theside member 5, as shown by dotted lines in Fig. 1, so that when themachine is placed on the surface to be sanded pinion I 6 on the motorshaft which meshes with 55 or polished, the weight of the machine comeson the lower run of the abrading belt I. The side member 5 is providedwith a bulge or extension i 3I at its rear lower cover which is situatedto the .yieldingly held against the belt. This tension pulley is mountedon the motor housing I6, for which purpose a supporting bracket 33 isprovided whichis secured to said motor housing. The tension pulley 32 ismade in two sections, 32a and 32h, said sections being rotatably mountedon a shaft 34 which is carried by an arm 35 that, in turn, is pivotallysecured to the supporting bracket 33, as shown at 36. The upper end ofthe bracket 33 is forked and the pivotal shaft 36 is mounted in the armsof the fork. One end of the arm 35 is located between the arms of theforked supporting bracket 33 and is pivotally mounted on the shaft 36.This supporting arm 35 extends between the two pulley sections 32a, 32hand provides a central support for the shaft 34.

The arm 35 has a depending stem 31 formed at its lower end with an eye38 through which extends a pin 39 projecting from and carried by thebracket 33. 40 indicates a spring surrounding the pin 39 and confinedbetween the stem 31 and the bracket 33, said spring 40 thus operating toyieldingly hold the pulley section 32a, 32h against the abrading belt,thus maintaining it under proper tension.

The pulley 32 is not only a tension Pulley but also an alining pulley,in that it functions to maintain the belt properly lined up.

The supporting bracket 33 is secured to the motor housing l0 in such away that said bracket can be turned about a horizontal axis extendingfore-and-aft of the frame,'thereby to maintain connected to the lowerend thereof, as shown at I 43, said link extending through the sideframe 5 and having a screw-threaded end 43 on which is screw-threaded athumb piece 44 that bears against the side frame 5. The link 42 isprovided with a shoulder 45, and a spring 46 encircles the link and isconfined between said shoulder 45 and the side member 5 of the frame.

By turning the thumb piece 44 in one direction or the other, the bracket33 will be turned or adjusted about its pivot 4|, and thereby the axis Iof the tension pulley 32 may be maintained in proper parallel relationwith the axis of the idler 3.

I have also shown means whereby the yielding pressure of the tensionpulley 32 against the belt may be reduced or entirely removed. Extendingthrough the end of the pin 39 is a shaft 50 which has cam members 41mounted thereon that bear against the outside of the arm 31. This shaft50 extends through an opening 48 in the side portion 5 of the frame, andthe outer end thereof is bent laterally as shown at 49 to provide afinger piece by which the shaft may be turned. When the shaft is turnedcounterclockwise in Fig. 1, the cams 41 act against the stem 31 and thusswing the arm 35 downwardly, which will result in relieving the yieldingpressure of the tension roll 32 against the under side of the belt.

5| indicates a hand grip which is secured to the top member 1 and whichprovides means by which the person operating the apparatus can applypressure thereto as needed for properly sanding the surface beingtreated.

This hand grip 5| not only provides means for applying pressure to theabrading machine, as above set forth but, together with the point 56 ofthe handle 28, it provides a three-point support on which the machinemay be supported in inverted position, the two ends 51 of the hand grip5| and the point 55 of the handle 23 providing the three points ofsupport. When the abrading machine is thus supported in an invertedposition and is set in operation, it can be advantageously used forsanding or polishing small pieces by holding the pieces against theexposed portion of the abrading belt when the machine is in its invertedposition.

I claim:

1. An abrading machine comprising a frame, a driving pulley mountedthereon, an idler pulley, an abrading belt passing around said pulleys,a motor housing situated between said pulleys and between the upper andlower runs of the abrading belt, a motor mounted in said housing,driving connections between the motor and the driving pulley, asupporting bracket mounted on the motor housing for turning movementabout a horizontal axis extending fore-and-aft of the frame, a tensionpulley yieldingly mounted on said bracket and engaging the abradingbelt, and means for adjusting the supporting bracket about its axis tovary the angular relation between the tension pulley and the idlerpulley.

2. An abrading machine comprising a frame, a driving pulley mountedthereon at the rear end thereof, an idler pulley at the front end ofsaid frame, an abrading belt passing around said pulleys, a motorhousing situated between said pulleys and between the upper and lowerruns of the abrading belt, a motor mounted in said housing, drivingconnections between the motor and the driving pulley, a supportingbracket pivotally mounted on the motor housing to turn about ahorizontal axis extending fore-and-aft of the frame, a tension pulleycarried by said bracket, means for yieldingly holding the tension pulleyagainst the abrading belt, and means for adjusting said bracket byturning it about its horizontal axls.

3. An abrading machine comprising a frame having two side members, amotor housing situated between and mounted on said side members, a motorin the motor housing, a single relatively large pulley carried by theframe at the rear end thereof, said pulley constituting a drivingpulley, a forwardly extending arm secured to the motor housing, arelatively small idler pulley rotatively mounted on said arm andsituated at the front end of the frame near the lower side thereof, anabrading belt passing around said pulleys, the motor housing beingsituated between the upper and lower runs of said belt, a supporting armpivotally mounted on the motor housing at the front side thereof, atension pulley carried by said arm and engaging the abrading belt and aspring acting on said arm and yieldingly holding the tension pulleyagainst said belt.

4. An abrading machine comprising a frame having two side members, amotor housing situated between and mounted on said side members,

a motor in the motor housing, a single relatively large pulley carriedby the frame at the rear end thereof, said pulley constituting a drivingpulley, a forwardly extending arm secured to the motor housing, arelatively small idler pulley rotatively mounted on said arm andsituated at the front end of the frame near the lower side thereof, anabrading belt passing around said pulleys, the motor-housing beingsituated between the upper and lower runs of said belt, a supporting armpivotally mounted on the motor housing at the front side thereof, atension pulley carried by said arm, a stem depending from said arm, anda spring interposed between said stem and the motor housing andoperating to yieldingly hold the tension pulley against the belt.

5. An abrading machine comprising a frame having two side members, amotor housing situated between and mounted on said side members, a motorin the motor housing, a single relatively large pulley carried by theframe at the rear end thereof, said pulley constituting a drivingpulley, a forwardly extending arm secured to the motor housing, arelatively small idler pulley rotatively mounted on said arm andsituated at the front end of the frame near the lower side thereof, anabrading belt passing around said pulleys, the motor housing beingsituated between the upper and lower runs of said belt, a supportingbracket pivotally mounted on the front side of the motor housing to turnabout a horizontal axis extending fore-and-aft of the frame, an armpivotally mounted on said bracket to turn about a transverse horizontalaxis, a tension pulley carried by said arm, said arm having a dependingstern, a spring interposed between said stern and said bracket forholding the tension pulley yieldingly against the belt, and means foradjusting the bracket about its horizontal axis.

6. An abrading machine comprising a frame having two side membersconnected by a top member in the form of a hood having downwardlydirected end portions, a driving pulley and an idler pulley mounted onthe frame, an abrading belt passing around said pulleys, the upper runof said belt passing underneath the hood, a motor housing carried by theframe and situated between said pulleys and between the upper and lowerruns of the abrading belt, a motor in said motor housing, drivingconnections between the motor and the driving pulley, a handle mountedon said hood at the rear end thereof, and a hand grip separate vfrom thehandle and mounted on said' hood adjacent the front end thereof, saidhand grip presenting a bar extending transversely of the hood and havinga concavely curved upper surface, the two ends of said bar together withthe handle forming a three-point support for the abrading machine whenit is in inverted position.

ARTHUR C. BURLEIGH.

